Following which event has evolution happened?
a. an allele frequency in a population changes over time.
b. a new predator comes into an environment.
c. an individual is born with six fingers on one hand instead of five.
d. an animals white coat is replaced by a darker coat in the spring.

Molecules like glucose and amino acids are not lipid soluble, so cannot cross the cell membrane by simple diffusion. instead, they are shuttled across by carrier proteins in the membrane from high to low concentration. does this process require energy from the cell? this is an example of what type of molecular movement?